Perhaps you should try some spelling variations:
sach tranh » canh tranh
sach ngan » sach ngon, sach nha, sach han
kxy thuat » ky thuat, ki thuat, my thuat
toan hoc » toan khoa, van hoc, hoa hoc
tu sach » thu sach, su sach, te sach
y thuat » ky thuat, my thuat, ki thuat
thuat o » thuat do
ngan y » nganh y, nhan y, nganh ky
o hoc » co hoc, mo hoc, so hoc

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu sach ngan y thuat o hoc ) or ( tu sach tranh kxy thuat toan hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach ngan y thuat o hoc ) OR ( tu sach tranh kxy thuat toan hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach ngan y thuat o hoc ) or ( tu sach tranh kxy thuat toan hoc ))*.